High-speed penumatic switch



Aug. 15 1967 "r. J. HARRIS ETAL 3,335,755

HIGHSVPEED PNEUMATIC SWTTCH Filed Oot 15. V1965 3 Sheets-$heet 1 FIG. I

MOVING COIL- ACTUATOR ASSEMBLY a T0 TERMINALS FIGURE 2 VACUUM 1' 32 TO M-34q 32b 34b TA PE ORIF'ICE PRESSURE I I l' '1 43 MOVING con. l ACTUATORE fi ASSEMBLY 1 T0 TERMINALS v '"f-- 555 INVENTDRS JESSE LAWEIDA moms J.HARRIS AGENT Aug. 15, 1967 Filed Oct. 15. 1965 1'. J. HARRIS ETALHIGH-SPEED PNEUMATIC SWITCH 3 Sheets-Sheet 3 "con CURRENT SWITCH s2FROM; no. 4

1 TBT United States Patent 3,335,755 HIGH-SPEED PNEUMATIC SWITCH ThomasJ. Harris and Jesse I. Aweida, Poughkeepsie,

N.Y., assignors to International Business Machines Corporation, Armonk,N.Y., a corporation of New York Filed Oct. 15, 1965, Ser. No. 496,283 7Claims. (Cl. 137-624.15)

This invention relates to hydraulic control systems and moreparticularly, to hydraulic valves employed in controlling flow of fluidthrough hydraulic systems.

Hydraulic tape transport mechanisms which use pressure and vacuum tocontrol the movement of tape are Well known in the art. Capstans areprovided which rotate in opposite directions and over which the tapepasses. Vacuum is applied through ports in one of the captans andpressure is applied through ports in the other capstan to drive the tapein contact with the first capstan and out of contact with the secondcapstan. In this manner, the tape is caused to move in the direction ofrotation of the capstan which has vacuum applied to it. The tape motionis reversed by reversing the sense of vacuum and pressure. The speed forswitching from one direction to the other is limited by the timerequired to change the conditions of vacuum and pressure under the tapeat each capstan.

Existing mechanisms for applying vacuum or pressure to tape employ adiaphragm located within the capstan. When the diaphragm is seated inone position, pressure is applied to the tape through orifices in thecapstan. When the diaphragm is seated in the opposite position, vacuumis applied to the tape. A push-pull electromagnetic motor attached tothe diaphragm pushes or pulls the diaphragm to each seating position.The switching speed is limited by the time required to move thediaphragm and the motor armature from one position to the other. Sincethe diaphragm is moved from a standstill position, the switching time isrelatively large because high inertia forces must be overcome.

It is therefore a paramount object of this invention to provide ahigh-speed hydraulic valve.

It is a further object of this invention to provide a high-speedhydraulic valve for controlling the flow through a plurality ofpipelines.

It is also an object of this invention to provide a hydraulic valvewhich will rapidly switch from a vacuum condition to a pressurecondition in a hydraulic tape system.

The above objects are accomplished in accordance with the invention byproviding sliding valve members moving in harmonic motion past fixedorifices, either in phase or 180 out of phase with respect to eachother. The valves have openings located such that when the valves areoscillating in phase, pressure is applied to the tape; and when thevalves are operating out of phase, vacuum is applied to the tape.Pressure or vacuum is electronically switched by changing the phase ofthe oscillating members.

The invention has the advantage that since the members move in apredictable manner, wear on the sliding surfaces can be greatly reducedby thin air films between the moving parts. The members sliding inharmonic motion do not require high initial forces for rapid switching,do not have overshoot, and do not require valve seating.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings.

In the drawings:

3,335,755 Patented Aug. 15, 1967 ICC FIG. 1 is a cross-sectional view ofa hydraulic valve in which the present invention is embodied;

FIG. 2 is a schematic diagram of an electrical circuit which may be usedto control the switching of the valves shown in FIG. 1;

FIG. 3 is a timing diagram illustrating the waveforms produced by thecircuit of FIG. 2; and

FIGS. 4 and 5 are more detailed diagrams of the switching circuit shownin FIG. 2.

The invention may be summarized with respect to FIG. 1. A hydraulicvalve body 10 has inlet pipe orifices 12 and 14 for supplying pressureor vacuum respectively to an outlet pipe orifice 16 which communicateswith the capstan of a hydraulic tape drive (unshown). Located within thehydraulic valve 11) are two oscillating members 29 and 22 which aredriven by push-pull electromagnetic (moving coil) motors 24 and 28. Themotors 24 and 28 are controlled by the circuitry shown in FIG. 2.

The vacuum and pressure pipes feed into ducts 30, 32, 34, and 36 whichcommunicate with orifices 38, 40 and 42 in the oscillating member 29.The ducts 30, 32, 34, and 35 continue through the hydraulic valve 10 tothe tape orifice 16. The sections are labeled 30a, 30b, 32a, 32b, etc.

The oscillating member 21 has orifices 38, 40, 42 cut therein. Theseorifices communicate with the ducts to allow fluid (vacuum or pressure)to pass through the duct 30 and the orifice 38, and through the duct 36and the orifice 42 when the member is in the lowermost extremity of itsmovement. When the member 21 is in the uppermost extremity of itsmovement, fluid passes through duct 32 and orifice 4t), and through duct34 and orifice 42. i

The oscillating member 22 has orifices 44, 46 and 48 cut therein. Theseorifices communicate with the ducts to allow fluid to pass through theduct 312a and the orifice 44 and through the duct 34a and the orifice 48when the member is in the uppermost extremity of its movement. Theorifices 46 and 48 allow fluid to pass through the ducts 32a and 3611when the member 22 is in the lowermost extremity of its movement. Whenthe members oscillate in phase, pressure is applied to outlet 16, andwhen the members oscillate out of phase, vcauum is applied.

A detailed description of the hydraulic valve shown in FIG. 1 and thecircuitry for controlling the operation thereof shown in FIGS. 2, 4, and5, follows. The hydraulic valve assembly is comprised of a stationaryportion 10 and moving members 21 and 22 which are moved by moving coilassemblies 24 and 28. Moving coil as sembly 24 is shown in detail andincludes a permanent magnet 5th, a soft-iron return path 52, a soft-ironmagnetic cap 54, a moving coil bobbin 56 (with a coil 58 wrapped aroundit) and a restoring spring 60. The moving coil in the assembly 24 isattached to the output leads A and B. The maximum displacement of theelement 20 is limited by a protrusion 62 which limits the motion betweenan element stop 64 and the valve housing 10. A similar arrangement isprovided for the moving element 22.

The moving coils are controlled by the circuits shown in FIG. 2.Referring to FIG. 2, a sine wave signal from the generator 40 is appliedto the coil 58 through switches S2 and S1, causing the currents in thecoils to vary. The pulse generator 70 generates a square wave pulsewhich is in phase with the sine wave from the pulse generator 40. Whenswitch S1 is transferred opposite to the position shown, the square wavepulse is applied to the coil 58 at time T1 (see FIG. 3) for a durationof onehalf the period of the sine wave. At time T2, the switch S1 isreturned to its normal position. At the same time, switch S2 is switchedto the position opposite to that shown in the drawing to reverse thephase of the signal (from sine wave generator 40) applied to the coil58.

A current waveshape of the type shown in FIG. 3 causes the element '20to stop completely at time T1 for one-half a cycle completing a 180phase shift at time T2. The switch S1 is operated when the velocity ofthe element 20 is zero. When this occurs, the displacement of theelement 20 is maximum and all of the energy of the mechanical system isstored in the spring 60.

Switch S1 is shown in detail in FIG. 4 and switch S2 is shown in detailin FIG. 5. The purpose of S1 is to provide a 180 phase shift in therelative motion of the moving elements 20 and 22. Once this isaccomplished, the coil currents and driving voltages are in phase withthe oscillation of the moving parts.

Referring to FIG. 4, the square wave generator 70 includes an amplifier72 and a clipping circuit 74. The input C, D to the amplifier 72 isprovided from the sine wave generator 40, shown in FIG. 5. The output C,D of the sine wave generator also drives a phase shift circuit 82, theoutput of which is amplified by amplifier 84 and clipped by clippercircuit 86. The output from the clipper circuit 86 is a square wavewhich is differentiated by dilferentiator 88 and mixed by diodes 90 toprovide a series of positive pulses at the zero crossings of the sinewave generator output signal. These pulses are provided to one leg ofthe AND circuit '78. A trigger 76 is provided, the output of whichenergizes the other leg of AND circuit 78. The output of the AND circuit78 drives a single-shot multivibrator 80. The actual switching operationof switch S1 is accomplished by transistors T1, T2, T3, and T4 which arecontrolled by the output from multivibrator 80.

The switch S2 shown in FIG. is also controlled by the multivibrator 80and is comprised of transistors T5, T6, T7 and T8. Current is applied tocoil 68 via terminals E and F attached to the output of pulse generator40. Assuming that binary trigger 92 is turned off, the 1 output isnegative, causing transistors T5 and T6 to conduct, thus connecting theoutput of sine wave generator 40 to terminals C and D.

Referring now to FIG. 4, the output of multivibrator 80 is normallynegative so that the transistors T1 and T2 are conducting, thus applyingthe outputs C and D of switch S2 to the terminals A and B of coil 58.

A signal to change the relative phase of moving elements and 22 issupplied to the trigger 76 via set input 75. The trigger 76 is turnedon, thus energizing one leg of the AND circuit 78. The outputs C and Dof switch S2 (FIG. 5) drive a phase shift circuit 82 which adjusts fordelays in the circuitry. The sine wave signal is amplified by amplifier84 and clipped by clipper 86 to thereby provide a square wave voltage inphase with the signal generator 40. The output of clipper 86 isdifferentiated by the circuit 88 shown within the dotted lines. Thepositive and negative differentiating spikes are mixed together byrectifying diodes 90 to provide positive spikes occurring at the zeroaxis crossings of the sine wave generator output. These spikes are gatedvia AND circuit 78 to energize the multivibrator 80 and reset thetrigger 76. The output of the multivibrator 80 is a positive voltagewhich is maintained for one-half the cycle of the sine wave generator.That is from the time ii to the time 12 shown in FIG. 3. The output 81from the multivibrator 80 turns off transistors T1 and T2 and turns ontransistors T3 and T4. This applies the output of the pulse generator 70to the terminals A and B of coil 58. The output of pulse generator 70 isa high-amplitude step voltage occurring in phase with the sine waveinput to the amplifier 72. Thus, the step voltage occurring at time tlluntil time t2 in the waveform shown in FIG. 3 is generated.

The output of multivibrator 80 also drives a differentiator 83 whichdevelops a positive and a negative voltage spike corresponding,respectively, to the leading and trailing edges of the multivibratoroutput. The output of the differentiator drives a binary trigger 92shown in FIG. 5. The positive output 85 sets the binary trigger to itsopposite state, thus causing the output of the trigger to go positive.This causes transistors T5 and T6 to cease conducting and turns ontransistors T7 and T8. The phase-shifted output of the sine wavegenerator 40 is now applied to the terminals C, D of the switch S2.

When multivibrator 80 (FIG. 4) has timed out, its output 81 drops,causing transistors T1 and T2 to again conduct, turning off transistorsT3 and T4. The square wave pulse generator 70 is now disconnected fromthe terminals A and B and the phase-shifted output pulse on ttrminals C,D is connected to the terminals A and B at time t2 in the cycle (FIG.3).

In summary, the invention comprises a hydraulic valve 10 having movingelements 20 and 22 which move either in phase or 180 out of phase withrespect to each other under control of electromagnetic moving coilactuators 24 and 28. When the elements 20 and 22 are operating in phase,that is, moving in the same direction with respect to each other,pressure is applied to the tape orifice 16 via ducts 34, 34a, 34b, andducts 36, 36a, 36b alternately through cooperation with the orifices 42,48.

Vacuum is supplied via duct 12 to the tape orifice 16 when the movingcoil actuators are energized to cause the elements 20 and 22 tooscillate 180 out of phase with respect to each other. Thus, vacuum issupplied through the ducts 30, 30a, 30b, and the ducts 32, 32a and 32bthrough the action of the orifices 38 and 44 and the orifices 40 and 46,which alternately open and close the ducts.

The invention has been described with respect to a magnetic tape system;however, the valve may be used in other hydraulic systems such as, butnot limited to, computer fluid logic and fluid pipelines. Further, theinvention is not limited to moving coil control means, but may employother electromotive powering or mechanical linkages.

Only two reciprocating valves have been illustrated; however, any numberof oscillating valves may be utilized to control the flow through two ormore pipes, by extending in an obvious manner the teachings of thisinvention. For example, if three pipes are to be controlled, threereciprocating members should be provided. Flow through the first pipewould require in-phase operation of all three members; through thesecond pipe, in-phase operation of the first two members andout-of-phase operation of the third; and flow through the thirdpipewould require in-phase operation of the second and third members, whilethe first member operates out of phase therewith. The location of theorifices in the members can be easily determined by one having ordinaryskill in the art.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made therein Without departing from the spirit andscope of the invention.

What is claimed is:

1. A system for controlling flow through a plurality of pipelinescomprising:

inlet and outlet orifices for each pipeline; and

reciprocating elements in series between said orifices,

said elements adapted to oscillate both in phase and out of phase withrespect to each other past said orifices;

said elements and pipelines having openings therein located with respectto each other such that when said elements are oscillating in phase, atleast one' elements are oscillating out of phase, the first-mentionedpipeline remains closed during the entire oscillation while said otherone of said pipelines is opened in each extremity of operation andremains open during the oscillation except for a brief periodintermediate the oscillation, to thereby permit or impede the flow ofthe fluid through said pipeline, depending upon the relative phase ofreciprocation of said elements.

2. The combination according to claim 1 including means forreciprocating said elements which means includes switching meansfor'stopping the motion of one of said elements when the velocity ofsaid element is substantially equal to zero and for starting saidstopped element one-half cycle after said element has stopped to therebycause said element to reverse its phase of oscillation, with respect tothe other reciprocating elements.

3. The combination according to claim 2 wherein said reciprocating meansfurther includes:

moving coil electromagnetic motors for driving each element and saidswitching means includes: a sine wave signal source constantly appliedto at least one of said moving coils;

a square wave signal source synchronised with said sine wave source;

selection means for selectively connecting said sine wave source andsaid square wave source to the moving coil of the element to be stopped;

phase reversal means for reversing the phase of said sine wave signalapplied to the moving coil of the element to be stopped and meansoperative upon energization of said switching means for causing saidselection means to connect the square wave source to the moving coil ofthe element to be stopped for one-half of a cycle, for reversing thephase of said sine wave signal, and for causing said sine wave signal tobe re-applied to said moving coil at the end of said one-half cycle.

4. A system for controlling the flow through a plurality of pipelinescomprising:

first inlet and outlet pipes, each having first and second second inletand outlet pipes, each having first and second orifices;

first and second elements adapted to be moved sinusoidally havingorifices therein located with respect to the first and second orificesof said pipes so that when the first element is in one extremity ofmovement, the first orifice of said first inlet pipe is closed and thesecond orifice is opened and the first orifice of said second inlet pipeis opened and the second orifice closed and when said first element isin the opposite extremity, the first orifice of said first inlet pipe isopened and the second orifice of said first inlet pipe is closed and thefirst orifices of said second inlet pipe is closed and the secondorifice of said second inlet pipe is opened;

said second element having orifices located such that when the secondelement is in one extremity of movement, the first orifice at said firstoutlet pipe is opened and the second orifice is closed and the firstorifice at the outlet of said second pipe is opened and the secondorifice is closed; and when said second element is in the oppositeextremity of operation, the first orifice at the outlet of said firstpipe is closed and the second orifice is opened and the first orifice atthe outlet of said second pipe is closed and the second orifice isopened;

whereby when said oscillating elements are oscillating substantially inphase with respect to each other, the orifices at the inlet and outletof said second pipe are opened in each extremity of operation of saidelements, and when said elements are oscillating substantially out ofphase, the orifices at the inlet and outlet of said first pipe areopened in each extremity of operation of said elements.

5. A system for controlling flow through a plurality of pipelinescomprising:

inlet and outlet orifices for each pipeline; and

reciprocating elements in series between said orifices,

said elements adapted to oscillate both in phase and out of phase withrespect to each other past said orifices;

said elements and pipelines having openings therein located with respectto each other such that when all of said elements are oscillating inphase, one of said pipelines is opened in each extremity of operation ofsaid elements and remains open during the oscillation except for a briefperiod intermediate the oscillation, while another of the pipelinesremains closed during the entire oscillation, and when at least one ofsaid elements is oscillating out of phase with respect to the remainingelements, the first-mentioned pipeline remains closed during the entireoscillation while said other one of said pipelines is opened in eachextremity of operation and remains open during the oscillation exceptfor a brief period intermediate the oscillation, to thereby permit orimpede the flow of the fluid through selected ones of said pipelinesdepending upon the relative phase of reciprocation of said elements.

6. The combination according to claim 5 including means forreciprocating said elements which means includes switching means forstopping the motion of one of said elements when the velocity of saidelement is substantially equal to zero and for starting said stoppedelement one-half cycle after said element has stopped to thereby causesaid element to reverse its phase of oscillation, with respect to theother reciprocating elements.

7. The combination according to claim 6 wherein said reciprocating meansfurther includes:

moving coil electromagnetic motors for driving each element and saidswitching means includes: a sine wave signal source constantly appliedto at least one of said moving coils;

a square wave signal source synchronised with said sine wave source;

selection means for selectively connecting said sine wave source andsaid square wave source to the moving coil of the element to be stopped;

phase reversal means for reversing the phase of said sine wave signalapplied to the moving coil of the element to be stopped and meansoperative upon energization of said switching means for causing saidselection means to connect the square wave source to the moving coil ofthe element to be stopped for one-half of a cycle, for reversing thephase of said sine wave signal, and for causing said sine wave signal tobe ire-applied to said moving coil at the end of said one-half cycle.

ALAN COHAN, Primary Examiner.

1. A SYSTEM FOR CONTROLLING FLOW THROUGH A PLURALITY OF PIPELINES COMPRISING: INLET AND OUTLET ORIFICES FOR EACH PIPELINE; AND RECIPROCATING ELEMENTS IN SERIES BETWEEN SAID ORIFICES, SAID ELEMENTS ADAPTED TO OSCILLATE BOTH IN PHASE AND OUT OF PHASE WITH RESPECT TO EACH OTHER PAST SAID ORIFICES; SAID ELEMENTS AND PIPELINES HAVING OPENINGS THEREIN LOCATED WITH RESPECT TO EACH OTHER SUCH THAT WHEN SAID ELEMENTS ARE OSCILLATING IN PHASE, AT LEAST ONE OF SAID PIPELINES IS OPENED IN EACH EXTREMITY OF OPERATION OF SAID ELEMENTS AND REMAINS OPEN DURING THE OSCILLATION EXCEPT FOR A BRIEF PERIOD INTERMEDIATE THE OSCILLATION, WHILE ANOTHER OF THE PIPELINES REMAINS CLOSED DURING THE ENTIRE OSCILLATION, AND WHEN SAID ELEMENT ARE OSCILLATING OUT OF PHASE, THE FIRST-MEMTIONED PIPELINE REMAINS CLOSED DURING THE ENTIRE OSCILLATION WHILE SAID OTHER ONE OF SAID PIPELINES IS OPENED IN EACH EXTREMITY OF OPERATION AND REMAINS OPEN DURING THE OSCILLATION EXCEPT FOR A BRIEF PERIOD INTERMEDIATE THE OSCILLATION, TO THEREBY PERMIT OR IMPEDE THE FLOW OF THE FLUID THROUGH SAID PIPELINE, DEPENDING UPON THE RELATIVE PHASE OF RECIPROCATION OF SAID ELEMENTS. 